1. Field of the Invention
This invention relates to the field of optical switching. The switching mechanism is a micro-mechanical movement of a cantilever device induced by optical absorption, in a wave guide material, of photons above the energy band gap of the material.
The effect can be used to modulate or switch an optical channel and may be cascaded to form an ultrahighspeed network switch.
2. Background
Micro-mechanical sensors measure physical quantities by utilizing variations in the physical properties of fabricated microstructures. Advances in micro-fabrication techniques have resulted in improved dynamic response, reduced size, high precision, reproduceability and reliability. Micro-mechanical mass-produced cantilevers of various shapes have been used in atomic force microscopes, scanning tunneling microscopes, and for the detection of chemicals (U.S. Pat. Nos. 5,719,324 and 5,445,008), for the detection of physical parameters such as force, acceleration, acoustics, flow rate, viscosity and temperatures [c.f. Thundat et al., Microscale Thermophysical Devices 1:185 (1997)] and as a specific infrared spectrometer [c.f. U.S. Pat. No. 5,977,544].
Optical switches present a technical challenge, and equipment available represents a compromise between optical throughput, rejection efficiency, speed, size and cost. For example, see U.S. Pat. No. 5,841,912 which discloses an optical switching device which employs an electrically triggered piezoelectric layer associated with an optical waveguide to switch by generation of an acoustical wave.
It is an object of this invention to provide an optical switch of a very small size for use in micro-miniaturized optical circuits.
It is a further object of this invention to provide an optical switch which can operate at speeds above 1 MHz.
It is another object of this invention to provide an optical switch which does not interfere with the operation of other switches and components of an optical device.
It is a further object of this invention to provide an optical switch which generates minimal heat while in use regardless of the rate of switching.
These and other objects may be achieved by using a micro-mechanical semiconductor beam as a waveguide and using photon-induced stress to direct a beam of light traveling through the waveguide. Photons impinging on the beam generate xe2x80x9cfreexe2x80x9d charge carriers in the beam which causes an increase or decrease in the lattice constant of the semiconductor, thereby causing the beam to bend reversibly.